Nu-(2-keto-3-oximinoalkyl)-p-aminobenzoate compounds



iatented Aug. 4, 1953 N- (z-xa-ro-a-ioxnvlmoatxn) i-Aimvd- BENZOATECOMPOUNDS David ILWeisblat' andBarney J Mage'rlein, Kalamazoo, Michassignors to The Upjohn Company, Kalamazoo, Michigan Mich a corporationof NoDi-avving. "Appllcation February 16,1952, Serial No. 271,982

*8 Claim.

This invention relatesto N-(2 keto-S-'oximinoalkyD-p-amincbenzoatecompounds and to a method-useful in "theirpreparati'on. application is acontinuation-in-part of co-pending application Serial No. 180,502, filedAugust 19, 1950.

The N- (2-keto-3-oximinoalkyl) p-aminobenzoate Compounds Iwhich can beprepared by the 'meth'odof the invention have the generic formula HON,oooR

N- (2-keto- 3-oximinoalkyl -p-aminobenzoate compound wherein R is amember of the :class consisting of hydrogen and the 'alkyl radicals, nisa member of the class consisting of zeroand-the positive integer 1 andRis a member of-theclass consisting of hydrogen and the alkyl radicals.In the structural formulae given herein and ingthe appended claimsaromatic vnuclei are represented by one or-mre simple hexagons.

Compounds having the 'genericiormula given are useful, as described andclaimed in co-pendi-ng application-Serial No.;180,5 02, inthepreparation of certain compounds related to the-folic acids. Thus,the N-(2-keto-3-oximinoalkyl) paminobnzoate compounds can be reactedreadily with 2,4,5-triamino-fi-hydroxypyrimidine to form certain-N-((2-amino--hydroxy-6-pteridyl) -methyl) p amino benzoate compoundswhich, uponhydrolysis of the ester groups and splitting of thep-toluenesulfonyl radical from the molecule with'hydrogen bromide and abromine accepter, are converted readily to compounds identical with or'very' similar to the folio acids isolated from natural sources.Inasmuch as the glutamic acid residues present in the latter compoundsisolated from natural sources generally'have the 'l(+) configuration,compounds having the generic "Formula I in which the glutamic acidresidue has the same configuration are ofsp'ecial value. V I

It is to be noted that when the 2-keto 3- oximinoalkyl radical of theN-(2ke to-3-oximinoalkyl) -p-amin'obenzoate Compound I contains morethan three carbon atoms, i. e. "when R of the generic formula given isan allgylradicaL-the N-( (Z-amino--hydroriy -6 '-'pteridy1) -methyl)p-aminobenzoate compound formed-is an N (;(2-amino-4-hydroxy-7-all-:yl-6-pteridi 'l) -met-hyl) p aminobenzoatecompound, there being an alkyl substituent in the 7 position of the-pterine nucleus. The alkyl substituted pteroic and folic acidswhich canbeprep'ared fromthem appear to be of considerable interest from aphysiological standpoint. The compounds of the invention are also usefulinorganic syntheses because of the proximity in the molecule of the ketoand oximino radicals.

Itis pointed out, ='also, that the method of the invention is"applicable to the preparation of compounds having the same formulaas-the generic formula-given but with n having a value greater than 1,eg. a value of '2 to 7, inclusive. Such compounds containing a pluralityof glutamic acid residues can have these residues connected by way ofthegamma carboxyl groups ofthe glutamic acid residues to form thepeptideulin'kage. It is pointed out, however, that the method isapplicable to the preparation of compounds wherein the alpha 'carboxylgroups ."OI' some. of the alpha andsome of the gamma carboxyl groups areinvolved in the peptide linkage.

In the naming of compounds having the generic formula given, and'ofother' com'pounds mentioned herein where .both a glutamic acid residueand a p-aminobenzoic acid residue are included in the molecule, thenitrogen atom of the glutamic acid residue-is, for convenience, hereinreferred to by the symbol N and the nitrogen atom of the p'-aminobenzoicaeidfre's'idue is referred to by the's'ymbol N.

' According to theinethod of the invention, as illustrated I in theaccompanying reaction chart wherein n, R. and R have thevalues givenpreviously, 7 l l- (2- keto-3 -oximinoalkyl) -paminobenzoate Compound Iisprepa'r'e'd'readily'by reacting an *alkyl nitrite in either an *acid'or an alkaline reaction medium, preferably in an acid medium, with anN-(Z-ketoalkyD-p-aminobenzoate compound havin'g'the Formula II.

o o o R cou h-2211011201120 o .o R

such as dioxane, diethyl ether, alcohol, tetrahydrofurane and the like.An organic liquid is preferably chosen in which the acid or alkalinecatalyst is at least somewhat soluble. Ethereal solutions of hydrogenchloride and alcoholic solutions of alkali metal alcoholates have beenused with satisfaction. Other acids and other alkaline substances can,however, be used, if desired.

Alkyl nitrites which can be used include n-butyl nitrite, tertiary-butylnitrite, iso-octyl nitrite, ethyl nitrite and the like. Insofar as isknown any alkyl nitrite can be employed. Substantially one mole, orsomewhat more, of the alkyl nitrite is preferably used for each mole ofketoalkyl compound. The reaction mixture is generally allowed to standat room temperature for from 6 to 12 hours, but higher temperatures canbe employed, if desired, and the reaction time shortened accordingly.

When a volatile acid catalyst is used to promote the reaction of analkyl nitrite with the ketoalkyl compound, the keto-oximincalkylcompound can be isolated conveniently by evaporating the volatilecomponents of the mixture under reduced pressure. When the reaction iscarried out in an alkaline medium, the keto-oximinoalkyl compound can beisolated readily by washing the reaction mixture with aqueous acid,subsequently drying the washed water-insoluble portion and evaporatingunder reduced pressure any volatile components which may be present. TheN-(2- keto 3 oximinoalkyl) -p-aminobenzoate compound is thus generallyrecovered as a viscous yellow sirup which is sufiiciently pure for mostpurposes.

An N (2-ketoalkyl)-p-aminobenzoate Compound II useful as a startingmaterial in the method of the present invention can be prepared, asdescribed and claimed in co-pending application Serial No. 180,501, byfirst reacting a l,2 epoxyalkane (III) having the formula RCHCH2 o III1,2epoxyalkane with an N-(arylsulfonyl) -p-aminobenzoate Compound IVhaving the formula C o R H-N oomnnomomoopoa and A0: 7 IV N-(arylsulfonyl) -p-aminobenzoate compound to form anN-(2-hydroxylalkyl)-p-aminobenzoate Compound V having the formula 0 o oR R-CHg-CHOH-CHg-N o 0 (NHr'JH CHzCHzCO),,OR'

My 0 2 V N- (2-hydroxyalkyl) -p aminobenzoate compound and subsequentlyoxidizing the hydroxyalkyl compound, e. g. with chromic anhydride inglacial acetic acid, 11., R and R having th values given previously. N(arylsulfonyl) -p-aminobenzoate Compound IV which can be employed withthe production of the corresponding intermediate and final compounds ofthe process include the N- (arylsulfonyl)p-aminobenzoic acids, theN'-(N- (arylsulfonyl) -p-aminobenzoyl) -glutamic acids, and their alkylesters.

Certain of the N-(arylsulfonyl) -p-aminobenzoate compounds are describedand claimed in copending application Serial No. 41,888, filed July 31,1948. They can be prepared readily as described therein by reacting anarylsulfonyl halide with p-aminobenzoic acid, N-(p-aminobenzoyl)glutamic acid, or with an alkyl ester thereof. N(arylsulfonyl)-p-aminobenzoate compounds which are esters can behydrolyzed readily to free acids with alkalies and the free acids can beesterified in conventional manner.

Esters having the generic Formula II which can be used as startingcompounds in the process of the invention with the production of thecorresponding esters having the generic Formula I include the methyl,ethyl, n-propyl, iso-propyl, butyl, amyl, hexyl, nonyl and many otheralkyl esters. As a matter of convenience, alkyl esters containing lessthan about 8 carbon atoms in the alkyl radical, preferably the ethylesters, are used in the process, although insofar as is known any alkylester can be used.

Although starting compounds containing substantially any arylsulfonylradical can be used in the process of the invention in the preparationof the corresponding final products (I), the preferred startingmaterials are those containing the p-toluenesulfonyl radical due to theready availability of the p-toluenesulfonyl halides and to the generallycrystalline nature of the p-toluenesulfonyl derivatives of compoundswith which the present invention is concerned. Th invention,

however, is not limited to compounds containing the p-toluenesulfonylradical, and compounds containing other arylsulfonyl radicals, such asthe o toluenesulfonyl, naphthalenesulfonyl, methylnaphthalenesulfonyland other arylsulfonyl radicals, can be used if desired. It should alsobe mentioned that compounds containing arylsulfonyl radicals havingnon-hydrocarbon substituents can be used in the process provided onlythat the substituent is non-reactive under the reaction conditions. Suchnon-reactive substituents include chlorine, bromine, and the methoxy,phenoxy, nitro and other radicals.

Although R in the Formulae I and II given represents hydrogen or anyalkyl radical, the preferred compounds are those wherein R is hydrogenand the invention has been described with particular reference thereto.Among the compounds that can be used in the process, if desired, arethose wherein R is the methyl, ethyl, npropyl, iso-propyl, n-butyl,tertiary-butyl, octyl or any other alkyl radical.

It is to be understood that the invention is not to be limited to theexact details of operation or exact compounds shown and described, asobvious modifications and equivalents will be apparent to one skilled inthe art, and the invention is, therefore, to be limited only by thescope of the appended claims.

Example 1.Diethyl N'-(N-(p-toluenesulfonyl) p-aminobenzoyl) -glutamateThirty and nine-tenths grams of p-toluenesulfonyl p amino benzoylchloride and 23.9 grams of diethyl l(+)-glutamate hydrochloride weredissolved in 300 milliliters of ethylene dichloride and the solutioncooled to between 0 and 10 C. The cold solution was stirred vigorouslyand 22.3 grams of triethylamine in '72 milliliters of ethylenedichloride was added slowly over a period of about 20 minutes. Thetemperature of the mixture was held between 10 and 20 C. during theaddition of the triethylamine and the mixture then allowed to stand atroom temperature for one hour. The mixture was then washed successivelywith water, dilute hydrochloric acid, saturated aqueous sodiumbicarbonate and finally with water. The-cgzvlgn less. solution thusobtained was dried withanhydrous sodium sulfate and naphtha was added,untilv the;

solution became opalescent. The mixture was then cooled to causecrystallization and filtered. The crystals, after drying, consisted of36 grams of diethyl -N'-(-N-(-petoluenesulfonyllip:aminobenzoyl)-l-glutamate melting at 12,49 to, 126 -10.

Example 2. Dieth'JZ N-(N(2-hyd'romypropyl)- N (p toluenesulfonyl) -paminobenzogl)'- glutamate A mixture of 6.38 grams of propylene oxide,47.? grams of diethyl N'(N-(p-toluenesulfonyl) p-aminobenzoyl)-glutamateand 10 drops of an hydrous pyridine was heated under pressure at, 130 C.for 2 hours. The reaction'mixture was then cooled to room temperature,400 milliliters of benzene were added and the resulting benzene solutionwas washed with 50 milliliters of water and 5.0- milliliters of dilutehydrochloric acid and then dried. Removal of the solvent under re-,duced pressure gave a non-crystalline solid resitoluene-sulfonyl)-p-aminobenzoyl) -glutamate.

In a similar manner, and using 1,2-epoxy-nbutane or1,2-epoxy-4-methyl-n-pentane in place of 1,2-epoxypropane, there areformed diethyl N (N (2 hydroxy n butyl) N (ptoluenesulfonyl) paminobenzoyl) glutamate sulfonyl)-p-aminobenzoyl)-glutamate leads, in

analogous manner, to the tormation of ethyl N (2 hydroxypropyl) N(benzenesulfonyl) p aminobenzoate or triethyl N (N (2 hydroxypropyl) N(p chlorobenzenesulfonyl) p aminobenzoyl) glutamyl glutamate,respectively. These esters, upon hydrolysis with dilute alcoholic sodiumhydroxide, are converted to N (2 hydroxypropyl) N (benz'enesulfonyl) paminobenzoic acid and N e (N (12-.

hydroxypropyl) N (p chlorobenzenesul fonyl) p aminobenzoyl) glutamylglutamic' acid, respectively. The free acids mentioned, uponesterification with an alkanol or with other alkyl ester-forming agents,are converted to the corresponding alkyl esters.

Example 3.Diethyl N (N 2- ketopropyD- N (p toluenesulfonyl) -paminobenzoyD- glutamate The crude diethyl N-(N-(2-hydroxypropyl)- N (ptoluenesulfonyl) p aminobenzoyD- glutamate obtained in Example 2 wasdissolved in 400 milliliters of benzene and the solution was added withvigorous stirring to a solution consisting of 52.6 grams of potassiumdichromate, 230 milliliters of water, 38 milliliters of acetic acid and69 milliliters of sulfuric acid. The mixture was stirred vigorously atto C. for about 2 /2 hours, cooled and the benzene and aqueous layersseparated. The aqueous layer was extracted twice with loo-milliliterportions of benzene and then discarded, the benzene extracts being addedto the benzene layer from the reaction mixture. The combined benzenesolutions were washed three times with ZED-milliliter por- 6 ion o W er.once w th 0D m l iiiters of; sat--- urat aqu ou o ium bicarbenate solemnwic w 250 li por o 01 e' e: and; Once h. 0 m ili er o saturated a ueousodi m. chloride solution- The wash d benzenesolution was. then dried ndh solven i t lled; under reduced p sure. The r sidue solvedin hotisopropanoland the solution r rystallizeat room. temp ra u e The wasfiltered and the crystals dried. There were us ned 34 .5 grams of: crudediethyl NV (N (,2 kfitopropyl) N. (p. toluen pyl) glutamate w ljch iqnn. r a ino, ,8 melted at'88" to 130 C. Recrystallization oi, the crudeketone raised its melting point to 99 to C.

Qxi-dation in a, similar manner of diethyl. N'- (N 2 hydroxy n b utyl)N' (p toluene sulfony-l) -1' p aminobenzoyl) glutamate, di-.. ethyl N (N(2 hydrox-y 4 methyl n1 pentyl) N (ptoluenesulfonyl) p amino-- benzoyl)glutamate, N" (N ("2 hydroxynv bu-tyl) N'- (p toluenesul-fony-l) pamino. ben'zoyl) glutamic acid, N (2 hydro xy-.

' propyl) N' (benzenesulfonyl) p aminobenzoic acid, ethyl N (2hydroxy-propyl) N- (benzenesulfonyl) p aminobenzoate, triethyl N (N (2hydroxypropyl) -'N- --(p chlorobenzenesulfonyl) p aminobenzoyl) lglutamylu a ate and N N (2- ydr xy tqmfll- (p, chlorotol-uenesulfonyll paminohenzoyl-lglutamyl glutamic acid gives diethyl Nf (N- (2 keto nbutyl) N (p toluenesulfonyl) p aminobenzoyl) glutamate, diethyl (N- (2keto 4 methyl n pentyl) N (p tol uenesulfonyl) p aminohenzoyl)glutamate, N (N (2 keto n butyl N (p etoluene sulfonyh p minobe zo s itni cidv N k p b N b nze esul qnyl P aininobenzoic acid, ethyl N 2ketopropyl)- -v N (benzenesulfonyl) p aminobenzoatei, tri-- ethyl N (N(2 ketopropyl N (p chlorobenzenesulfonyl) p aminobenzoyl) '7 lutarnyleglutamateand (N 2 kctopropyl) N'. (p chlorotoluenesulfonyl) paminobenzoyl utamy g t i sp ctivel Example 4.-Diethyl N (N(z-kcto-wximinwqpyl) -N (p-toluenesulfonyl) p aminobenza yl) -glutamateI A mixture of 1.0 gram of diethyl N -(N- (g-lgetopropyl) 1N(p-toluenesu ronyn -alt n be zgyl) -glutaniate, 15 milliliters Oanhydrous diethyl ether saturated with hydrogen chloride anddgtimilliliter of n-butyl nitrite was stirred at room temperature for 2 2hours and the volatilecomponents then volatilized under reducedpressure. There was thus obtained 1.05 grams of diethyl N"- (N-(2.-keto-.3-.oximinopropyl) ,N. (IJ-tolueneesulfonyl)-p-aminobenzoyl)glutamate, as a viscous yellow oil.

Other alkyl nitrites, such as ethyl nitrite, propyl nitrite and amylnitrite when reacted with diethyl N-(N-(2-ketopropyl) -N-(ptoluenesulfonyD-p-aminobenzoyl)-glutamate in the manner just describedlead to the formation of the same diethyl N-(N-(2-keto-3-oximinopropyl)-N- (p-toluenesulfonyl) -p-aminobenzoyl) -glutamate.

In similar fashion other esters, such as diethyl N-(N (2-keto-n-butyl)-N- (p-toluenesulfonyl) p aminobenzoyl) glutamate, diethyl N-(N-(2-keto-4-methyl-n-pentyl) -N-(p-toluenesulfonyl) p-aminobenzoyl)-glutamate, ethyl N-(2-ketopropyl) -N- (benzenesulfonyl)-p-aminobenzoate and triethyl N-(N-(2-ketopropyl)-N (pchlorobenzenesulfonyl) p aminobenzoyl) -glutamylglutamate, are reactedwith butyl nitrite to form diethyl N'-(N (2 --keto 3 oximino n butyl) N(p-toluenesulfonyl) -p-aminobenzoyl) glutamate, diethyl N-(N-(2-keto 3oximino-lmethyl-n-pentyl) -N- (p-toluenesulfonyl) -p-aminobenzoyl)-glutamate, ethyl N-(2-keto-3-oximinopropyl) N (benzenesulfonyl)p-aminobenzoate and triethyl N'-(N-(2-keto-3-oximinopropyl)N-(p-chlorobenzenesulfonyl) -p-aminobenzoyl) -glutamyl-glutamate,respectively.

Example 5.--Diethyl N-(N-(2-keto3-oximin0- prom/l)-N-(p-toluenesul,fo'nyl) p aminobenzoul) -glutamate A mixture of 1.0gram of diethyl N'-(N-(2- ketopropyl) -N-(p-toluenesulfony1)-p-aminobenzoyl) -glutarnate, 0.23 milliliter of n-butyl nitrite, 0.13gram of sodium methoxide and milliliters of benzene was stirred at roomtemperature for hours under an atmosphere of nitrogen. The benzenesolution was then extracted with an equal volume of dilute aqueoushydrochloric acid, then with an equal volume of water and dried. Uponvolatilization of the solvent under reduced pressure there remained 990mg. of diethyl N'- (N-(2-keto-3-oximinopropyl) -N-(p-toluenesulfonyl)-p-aminobenzoyl) glutamate as a viscous, yellow oily residue.

Example 6.N'-(N-(2-keto 3 oximinopropyl) N-(p-toluenesuljonyl)-p-amin0benzoyl) glutamic acid N(N-(2-keto 3 oximinopropyl)-N-(p-toluenesulfonyl)-p-aminobenzoyl) glutamic acid is preparedsubstantially as by the method of Example 4 by treatingN-(N-(2-ketopropyl) -N-(ptoluenesulfonyl) -p-aminobenzoyl) -glutamicacid with n-butyl nitrite in ethereal hydrogen chloride. The product isrecovered by volatilizing the low-boiling constitutents of the mixtureunder reduced pressure.

In similar fashion other acids such as N-(N- (Z-keto-n-butyl) -N-(p-toluenesulfonyl) -p aminobenzoyl) -glutamic acid, N-(Z-ketopropyl) N-(benzenesulfonyl) -p-aminobenzoic acid, and N'- (N-(2-ketopropyl) N(p-chlorobenzenesulfonyl) -p-aminobenzoyl) -glutamyl-glutamic acid arereacted with butyl nitrite to form N'-(N-(2-keto- 3 oxirnino-n-butyl)-N-(p-toluenesulfonyl) paminobenzoyD-glutamic acid,N-(Z-keto-B-oximinopropyl) -N-(benzenesulfonyl) -p aminoben- -zoic acidand N-(N-(2-keto-3-oximinopropyl)- N-(p chlorobenzenesulfonyl)-p-aminobenzoyl) glutamyl-glutamic acid, respectively.

We claim: 1. A compound having the formula rioN COOR R-(L-CO-GHz-NGO(NHCHCH|CHC0).OR'

aryl 01 wherein R is a member of the class consisting of hydrogen andthe alkyl radicals, n is a member of the class consisting of zero andthe positive integer 1 and R is a member of the class consisting ofhydrogen and the alkyl radicals.

2. A compound as claimed in claim 1 where- In the arylsulfonyl radicalis the p-toluenesulfonyl radical.

3. A compound having the formula HON c o O-alkyl HJ'.|!C0CH;-N C0NH(JHCH1CH:CO0-alkyl aryl Oz 4. A compound having the formula HON c o 0-alkyl 5. Diethyl N (N (2-keto-3-oximinopropyl)N-(p-toluenesulfonyl-p-aminobenzoyl) glutamate.

6. The method which comprises reacting a 2- ketoalkyl compound havingthe formula COOR aryl O 2 wherein R is from the group consisting ofhydrogen and the alkyl radicals, n is from the group consisting of zeroand the positive integer 1 and R is from the group consisting ofhydrogen and the alkyl radicals with an alkyl nitrite to form a2-keto-3-oximinoalkyl compound having the formula HON 00 o R B( /COCHzNcomm momcmoopo R aryl O:

ate.

DAVID I. WEISBLAT. BARNEY J. MAGERLEIN.

No references cited.

1. A COMPOUND HAVING THE FORMULA
 6. THE METHOD WHICH COMPRISES REACTINGA 2KETOALKYL COMPOUND HAVING THE FORMULA